We have reported that Aedes aegypti female mosquitoes possess a remarkable biological system to survive toxic ammonia concentrations released by blood meal digestion using previously unknown metabolic pathways present in this organism. Specifically, we have found that Ae. aegypti can detoxify ammonia by the same metabolic pathways that nitrogen fixing plants and bacteria use, unlike all other insects that have been studied. Mosquitoes can also use the nitrogen from the amide group of glutamine to produce uric acid as vertebrates do, and more surprisingly, mosquitoes hydrolyze uric acid into urea through the same metabolic pathway that some fish and amphibians use. Since the coordinated operation of these multiple metabolic pathways prevents a lethal ammonia concentration in the mosquito tissues after a blood meal, it impels us to know how these metabolic pathways are interconnected and regulated. Therefore, the main purpose of the grant application is to elucidate the metabolic regulation of nitrogen waste, as well as to analyze the flux of C and N molecules involved in ammonia metabolism in mosquitoes. These studies will be performed using a combination of RNA interference and mass spectrometry techniques. Attempts to control mosquito populations using biorational approaches depend on a thorough understanding of mosquito biology and metabolism. So, if the experiments that we propose are conducted successfully, they will open up new and exciting discoveries that could be applied for the design and implementation of better strategies for mosquito control. The following specific aims will be pursued: 1- Identify the mechanisms involved in the regulation of nitrogen waste in mosquitoes. 2- Investigate the flux of C and N molecules involved in ammonia metabolism in mosquitoes. According to our preliminary data, the metabolic regulation of nitrogen waste appears to be tightly- regulated in Ae. aegypti mosquitoes. Therefore, our objective is to understand how this regulatory mechanism controls the ammonia metabolism in adult female mosquitoes.